1. Field of the Invention
This invention relates to a man-machine interface which may be utilized to convey a direction of a detected target to a crew of an aerospace craft or a flight simulator, but it will be appreciated that this invention is also useful in other applications.
2. Description of the Prior Art
As a means of conveying detected information to a crew of an aerospace craft, displays have been often used. A CRT(Cathode-Ray Tube) is usually incorporated in a display and the detected information is shown on the CRT to the crew. Also, in aircraft which need to move vigorously, a HUD(Head Up Display) or a HMD(Head Mounted Display) has been used to present the detected information so that a pilot can get the information while looking ahead.
Detectors utilizing radar, infrared or laser aid crew in visual recognition. For instance, the crew can recognize targets in the distance which are invisible to the naked eye. The detectors can locate targets even under low visibility due to rain or cloud and check behind and to the sides where the crew can not look. One example making good use of such detectors is the F-15E fighter of the US Air Force. The F-15E fighters are usually fitted with LANTIRN(Low Altitude Navigation and Targeting Infrared for Night) pods in addition to radar. The LANTIRN pods include various sensors such as FLIR(Forward Looking Infrared) system, TFR(Terrain Following Radar), LTD(Laser Target Designator). Information about distance to target, azimuth angle and elevation angle captured by the sensors is displayed on the HUD situated in front of the crew. Thus, the crew can obtain information captured by the detectors via display as well as recognize targets by the unaided eye. However in either case, the crew obtains the information by visual perception. Though an audible alert is often used to inform the crew of the detected information, it is used mainly to call the crew's attention to an instrument panel or a display. Accordingly, the crew's eyes are always under a lot of stress.
Then, a known technology regarding sound, more specifically, binaural sound localization is explained as follows: binaural listening means listening by both ears and it is a usual situation in which we hear sound around us. We perceive the direction of and distance to a sound source binaurally and it is called sound localization. The theory and technology of binaural sound localization may be found in the literature, "Application of Binaural Technology" written by H. W. Gierlich in Applied Acoustics 36, pp.219-243, 1992, Elsevier Science Publishers Ltd, England; "Headphone Simulation of Free-Field Listening I: Stimulus Synthesis" by F. L. Wightman and D. J. Kistler in J. Acoust. Soc. Amer., Vol.85, pp.858-867, 1989; and "Headphone Simulation of Free-Field Listening II: Psychophysical Validation" by F. L. Wightman and D. J. Kistler in J. Acoust. Soc. Amer., Vol.85, pp.868-878, 1989. Furthermore, "Process and apparatus for improved dummy head stereophonic" by Peter Schone, et al, U.S. Pat. No. 4,388,494; "Three-dimensional auditory display apparatus and method utilizing enhanced bionic emulation of human binaural sound localization" by Peter Myers, U.S. Pat. No. 4,817,149; and "Surround-sound system with motion picture soundtrack timbre correction, surround sound channel timbre correction, defined loudspeaker directionality, and reduced comb-filter effects" by Tomlinson Holman, U.S. Pat. No. 5,222,059 have disclosed the technology. Thus, binaural sound localization is a technique for duplicating a more realistic sound in the audio industry. Still further, "Binaural Doppler radar target detector" by Ralph Gregg, Jr., U.S. Pat. No. 4,692,763 is related to a radar target detector and binaural technology.